U.S. Pat. No. 4,565,312 discloses a conventional powder actuated tool with safety. The conventional powder actuated tool includes a housing, a barrel, and a firing mechanism. The housing has a breech portion, a cradle portion telescopically connected to the breech portion, and a grip part extending from the breech portion. The barrel is mounted movably in the cradle portion, has an insert formed with a firing chamber for receiving an explosive powder cartridge, and defines a bore for receiving a fastener-driving ram. The firing mechanism includes a breech block, a firing pin and a trigger. A firing pin pawl is mounted in a blind hole in the firing pin, and is biased by a spring into a slot in the breech block. The slot has a searing surface that engages the firing pin pawl. A stop member is pivoted to the cradle portion, and has a tongue urged by a spring to protrude into a bore in the cradle portion to abut against the barrel, thereby preventing movement of the barrel relative to the cradle portion toward the breech block for positioning the explosive powder cartridge at a ready-to-fire position. Hence, the stop member can reduce the incidence of accidental drop fire.
In order to cock the tool and fire it, an operator must use one hand to depress the stop member to move the tongue out of the bore in the cradle portion to permit positioning of the explosive powder cartridge at the ready-to-fire position, and use the other hand to grasp the grip part to enable finger actuation of the trigger. Pulling the trigger causes the firing pin pawl to move into the blind bore and to disengage the searing surface, thereby releasing the firing pin from the searing surface and permitting movement of the firing pin, which is urged by a spring, toward the explosive powder cartridge.
Although the purpose of using both hands to cock and fire the tool is for safety considerations, it also causes inconvenience.